Craftsman gas weedeater. Engine runs, but the head won't run

Probably something wrong with the mount. You have a photo?

there is a cable that runs thru to the shaft take it apart at the shaft bottom and see if it is broken or unattached.

if it has a curved shaft check the cable they break went over loaded on both models check the clutch

Look under the mower to see if the drive belt has come off or broke. It is the belt that runs from the bottom of the engine to the rear axle.

Have an assistant start and hold the trimmer. At idle, there should still be a little drag on the clutches to make the shaft spin on that split shaft trimmer with the accessory head removed. No need to rev it or do anything fancy, but teamwork will make it safer.

Now forget about the engine and clutches - does the accessory head spin freely when turned by hand (removed from engine still!) and with a clear rotation of the shaft end visible inside the connector socket? Is the shaft end square with sharply defines angles, or rounded off? Does swapping in a different accessory function normally and as expected?

Sometimes the nub end of the shaft wears. Worse, the socket on the engine side has eaten itself to pieces. Worse, worse yet, clutches in the engine side that engage the accessory shaft are worn and there is simply no transmission of power. Good luck, hopefully this info will set your boots in the right direction!

yes, there is a spark module, but it's highly unlikely that two would have a bad module - more than likely, it is your gas mix. it must be fresh for the engine to run. the gas we have today will go bad in about a month and a half. if you happen to live in an area that has E85, forget it. small engines will not run very long, if at all on this junk. in some areas, you can get gas without alcohol, but it can only be used for lawn & garden equipment. it's expensive, but your engines will run

Check your carburettor mounting screws,they might be loose and it would mean the engine is
getting to much air and it would leak gas. Stephen

Clutch bearing is tight.

Probably fuel line into tank has hole in it, If over 5 years old these fuel lines become brittle and break easy. Go to local hardware or repair shop that has small engine parts and you should find the fuel lines. Be sure to take sample with you as there are many sizes. If you have trouble installing them get back to me. Be sure you know how the lines are routed before removing.